1. Field of the Invention
This invention relates to a paperboard container, and more particularly, a container which may be folded from a unitary blank wherein various panels of the blank are locked to other panels when the container is erected from the blank in such a manner as to retain the dimensional stability of the container when stacked and filled.
2. Description of the Prior Art
Most self-locking container designs detract from, rather than aid, in retaining the dimensional stability of the container when the container is erected from a single blank. When such containers are stacked on their sides, rather than bottom to top, the prior art containers do not perform satisfactorily. The stress on the side walls of the container cause any locking tabs on one wall received through another to loosen as the side walls collapse inwardly under pressure. Further, if such containers are used to ship produce, since most produce is shipped under high moisture conditions, the paperboard of the container tends to weaken and sag and the locking tabs become relatively ineffective.
The design innovations incorporated in the self-locking container of the present invention overcome most of the objections of the prior art designs discussed above. Particularly, the self-locking container of the present invention offers:
(1) minor top and bottom flaps which lock into the side wall panels and eliminate the racking or the side-to-side dimensional unstability of the container under load;
(2) locking tabs between overlapped bottom flaps which are held in position by a commodity packed within the interior of the container; and
(3) locking tabs on the minor top flaps which restrain the flaps against depressing, thus improving vertical stability, as well as lateral stability of the container under load.
Since the resultant, erected container is dimensionally stable, this also improves the ease of closing the container, as for example, by stapling. The lateral and vertical stability of the container is obtained by using a single, unitary paperboard blank, thus facilitating construction and making the design much less costly than in most prior art devices.